1. Field of the Invention
The present invention relates to a vehicle curtain airbag device that is inflated and deployed along a side surface of a vehicle interior for the purpose of protecting occupants in the event of a side crash or a rollover (lateral rollover) of a vehicle.
2. Description of the Related Art
A curtain airbag is provided above a door and is inflated and deployed along a side surface of a vehicle to absorb the load from the head part and the bust of an occupant. The curtain airbag is designed so as to protect (restrain) an occupant mainly in the event of a side crash. For example, pressure duration of the curtain airbag when it is inflated and deployed is longer than that of a front airbag or the like. This is because a side crash can lead to a rollover (lateral rollover) and the time in which an impact can occur may increase. In particular, in the event of a rollover, the danger of an occupant being ejected outside a vehicle through the side window increases. Thus, the curtain airbag restrains the occupant to prevent the occupant from being ejected outside the vehicle by maintaining the inflated state until a rollover finishes.
The curtain airbag is required to be reliably inflated and deployed to a vehicle side surface in order to absorb the load from an occupant and to realize an ejection preventing performance. Therefore, a “head protecting airbag device” disclosed in Japanese Patent Application Publication No. 2002-302005, for example, aims to provide a head protecting airbag device capable of generating high tension along a vehicle front-rear direction in a lower edge side of the airbag upon completion of inflation and deployment, in which when inflation gas is introduced and deployment and inflation of the airbag is completed, tension is generated in the front-rear direction in respective inflation shielding portions by respective inflating portions that are partitioned by partitioning portions in the inflation shielding portions. The inflation shielding portions are connected on the lower edge of the airbag by an inflation communication portion located below a planar portion to which inflation gas is not introduced. The inflation communication portion is disposed in the front-rear direction along the lower edge of the airbag and can connect the inflation shielding portions without decreasing the tension generated in the respective inflation shielding portions. Thus, it is possible to generate high tension in the front-rear direction along the entire lower edge of the airbag.
In recent years, in order to more reliably prevent ejection of occupants outside a vehicle in the event of a rollover, there is a demand for the curtain airbag to have a further improved performance (improvement in ejection preventing performance). To meet this demand, various persons skilled in the art have verified the ejection preventing performance at respective locations on a curtain airbag. At present, it is known that the ejection preventing performance of a curtain airbag tends to be poor on the end side (in particular, near the front end) than near the center in the vehicle front-rear direction. Here, as in the head protecting airbag device disclosed in Japanese Patent Application Publication No. 2002-302005, although the ejection preventing performance can be improved slightly by connecting a front end of the curtain airbag to a front pillar garnish, the improvement effect of that alone is not sufficient.